The HM Perpetual Moon is a testament to Arnold & Son's tradition of watches with astronomical indications.

The HM Perpetual Moon offers one of the most accurate moon phases on the market, with only one day's deviation every 122 years at which point a single push on the corrector will keep it in sync for another 122 years. The exceptional perpetual moonphase indication of this watch is a marvel in many ways. From the aesthetic side, the 29 mm moonphase disc, which runs from 10 to 2 o'clock on the dial, reveals one of the largest moons on the market with a diameter of 11.2 mm for the moon alone. Additionally, this large moon is one of the most visually stunning recreations of the moon because it is a three-dimensional sculptured moon that was first hand-engraved and then duplicated for the series. The sculptured moon is then inserted into the guilloché disc.

From the technical side, in addition to the HM Perpetual Moon being so precise, it is also an intriguing complication in that it is not simply a module added to the movement, but, in fact, is fully integrated into the caliber. The watch also has a unique easy-to-set feature thanks to the ingenious addition of a second moon indication installed at the back of the movement. This second moon display, visible via a transparent case back, features a graduated dial and a pointer hand that allows for a more exact setting.

Technical Specifications:
The case, in stainless steel, measures 42mm. It has double AR-coated sapphire crystals and it is water resistant to 30 meters.